Recent empirical evidence suggests a negative relationship between trade integration and income per capita convergence. We show that moderate reductions in trade posts can generate sizable increases in income per capita divergence in a neoclassical two-country model of trade and growth. The welfare of both countries, however, rises with trade integration due to changes in their consumption time paths. Our setup sheds light on the striking nonlinear growth in the trade share of output since World War II: a linear fall in trade costs over time produces an exponential increase in the trade share of GDP. Concerning the empirical relationship between openness and technological progress, we perform an exercise that cautions against the use of aggregate production functions to obtain Solow residuals: two countries that reduce their trade costs and experience no technological progress are measured to have positive TFP growth rates if an aggregate production function is used for that purpose.

Recent empirical evidence suggests a negative relationship between trade integration and income per capita convergence. We show that moderate reductions in trade posts can generate sizable increases in income per capita divergence in a neoclassical two-country model of trade and growth. The welfare of both countries, however, rises with trade integration due to changes in their consumption time paths. Our setup sheds light on the striking nonlinear growth in the trade share of output since World War II: a linear fall in trade costs over time produces an exponential increase in the trade share of GDP. Concerning the empirical relationship between openness and technological progress, we perform an exercise that cautions against the use of aggregate production functions to obtain Solow residuals: two countries that reduce their trade costs and experience no technological progress are measured to have positive TFP growth rates if an aggregate production function is used for that purpose.